I lubed some 405 gr bullets I had and ran them through the .457"
sizer then loaded up 50 rounds of black powder cartridges for the .45-70. I weighed all the charges for the cases. I was surprised that a 70 gr by volume charge of Goex FFg weighed 63.5 gr on my scale. I rounded it up to an even 65 gr by weight.
Each charge was poured down a drop tube, a .060" veggie wad pushed into the case and then the bullet seated so it was .050" off the rifling. I had to use a veggie wad because otherwise I wouldn't have enough compression on the black powder. The way I calculated it I have about 3/16" of compression which should be good.
When I cast me some 500 gr slugs I will likely not need the wads.
All I need now is a day with no rain so I can try them out. This is my first effort at shooting black powder cartridges and I was doing tons of research on it.

Dang! I wish I owned a Sharps! How about a picture or two of the fine weapon?

Sabotloader Check out page 2 or this forum near bottom "My New Toy".
Its not an original but a pedersoli reproduction.

OK I will - but you are right I was thinking it were an original peace of history

That is still a really good looking rifle!

Did you end up figuring out how to make primers?

No Younggun. I used Remington 9 1/2 primers. I figure they will be hot enough to ignite the FFg
The nice part is once I shoot these off I won't have to resize anymore. I can punch the primers out using a hammer and punch, wash and dry the cases, reprime and charge them again. Then just seat the bullets with a slight crimp.

I cast that same bullet in a LEE mold. They are .457-8 and I size them down to .451 for the White. As for the 70 grains, I would have weighed 70 grains. My understanding is in the old days their powder for their 45/70 was a weighed charge and not a volume charge. But I will be interested in seeing your range results. I always liked that rifle ever since Quigley Down Under movie.